Unity does lack of many builtin systems. The alternatives are generally overblown with complexity, trying to be a universal fit. So here is the stuff that could be imported simply by adding a git url and created with just right click. While these assets are the outcome of prototyping phases, they could serve their purpose in medium complexity projects.
- Unity 2021.3
https://github.com/amelkor/Game.git?path=/Assets/BSR/CharacterController
Create by right click on scene/inspector Game->Simple First Person Controller
note: currently requires com.unity.inputsystem being exactly 1.3.0 due to unresolved bugs in their 1.4 versions